This is pure speculation, or are you privy to board decisions at Github.

see above, git is not proprietary. nobody is trapped inside github at
all if nasty things happen.

Changes to the T&C's that substantially affect this can happen at any time.

lots of you also use gmail, g+ or other stuff, where i have more
concerns about abuse than at github...

This irrelevant in the context of ownership and copyright.

you came up with concerns against VC's. So in which context was this
meant then?

Without wanting to start a diatribe against VC's: the key term was
"beholden to". VC's are understandably interested in a quick and
substantial return on their investment and will do whatever it takes to
achieve that. They are not philanthropists and ownership is a key lever
for them. This is a fundamentally different proposition to paying for a
service from a company or setting up an organisation to do it yourself.
There is no free lunch.